Low temperature deposition of iridium containing films

ABSTRACT

Processing methods for forming iridium-containing films at low temperatures are described. The methods comprise exposing a substrate to iridium hexafluoride and a reactant to form iridium metal or iridium silicide films. Methods for enhancing selectivity and tuning the silicon content of some films are also described.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No.62/557,486, filed Sep. 12, 2017, the entire disclosure of which ishereby incorporated by reference herein.

FIELD

Embodiments of the disclosure relate to methods for depositing thinfilms containing iridium. More particularly, embodiments of thedisclosure are directed to methods of depositing iridium containing filmat low temperatures using iridium hexafluoride.

BACKGROUND

Metal silicides have important applications in semiconductor devices ascontacting materials. As device features becomes smaller, metalsilicides are critical to ensure the functionality of the advanceddevices due to their low resistance, good process compatibility, lowerelectromigration and good contact with other materials during theintegration process.

When metal silicides are used in a p/n contact, the p contact metalsilicide is more difficult to integrate because of its work functionrequirement. Another important requirement of the metal silicide is itsconformal deposition around the contact geometry surface. Therefore, anALD or ALD-like process of metal silicide is needed for integration.

Iridium is a newly proposed material for integration owing to its highmelting point (ability to withstand high current densities), exceptionaldensity, and ability to conduct electrical current. Iridium and iridiumcontaining thin films have attractive material and conductiveproperties. Iridium films have been proposed for applications from frontend to back end parts of semiconductor and microelectronic devices.

Iridium silicide (germanide) is an important candidate for p contactmaterial. There are not many iridium precursors suitable for metalliciridium processes or co-precursors for iridium silicide processes. Inparticular need are precursors for very pure iridium and relatedprocesses. These do not appear in publications or commercial products.

Thin-films of iridium and/or iridium silicide would ideally be depositedusing thin-film deposition techniques such as Chemical Vapor Deposition(CVD) and Atomic Layer Deposition (ALD) owing to their inherent abilityto deposit material in a high-throughput, conformal, and precisefashion.

Chemical vapor deposition (CVD) is one of the most common depositionprocesses employed for depositing films on a substrate. CVD is aflux-dependent deposition technique that uses precise control of thesubstrate temperature and the precursors introduced into the processingchamber in order to produce a desired film of uniform thickness. Thereaction parameters become more critical as substrate size increases,creating a need for more complexity in chamber design and gas flowtechnique to maintain adequate uniformity.

A variant of CVD that demonstrates excellent step coverage is cyclicaldeposition or atomic layer deposition (ALD). Cyclical deposition isbased upon atomic layer epitaxy (ALE) and employs chemisorptiontechniques to deliver precursor molecules on a substrate surface insequential cycles. The cycle exposes the substrate surface to a firstprecursor, a purge gas, a second precursor and the purge gas. The firstand second precursors react to form a product compound as a film on thesubstrate surface. The cycle is repeated to form the film to a desiredthickness.

The advancing complexity of advanced microelectronic devices is placingstringent demands on currently used deposition techniques.Unfortunately, there are a limited number of viable chemical precursorsavailable that have the requisite properties of robust thermalstability, high reactivity, and vapor pressure suitable for film growthto occur.

In addition, precursors that often meet these properties still sufferfrom poor long-term stability and lead to thin films that containelevated concentrations of contaminants such as oxygen, nitrogen, and/orhalides that are often deleterious to the target film application.Therefore, there is a need for improved deposition methods for thinfilms containing iridium.

SUMMARY

One or more embodiments of the disclosure are directed to a method ofdepositing an iridium-containing film. The method comprises exposing asubstrate surface maintained at a temperature in the range of about −25°C. to less than 250° C. to iridium hexafluoride and a reactant.

Additional embodiments of the disclosure are directed to a method ofselectively depositing an iridium metal film. The method comprisessequentially exposing a substrate surface maintained at a temperature inthe range of about −25° C. to less than 300° C. to iridium hexafluorideand a reactant comprising hydrogen. The substrate surface comprises afirst material consisting essentially of silicon and a second materialcomprising silicon oxide, silicon nitride or Al₂O₃. The iridium metalfilm is deposited with a selectivity greater than or equal to about 15and contains essentially no fluorine atoms and greater than or equal toabout 99.8% iridium atoms.

Further embodiments of the disclosure are directed to a method ofdepositing an iridium silicide film. The method comprises sequentiallyexposing a substrate surface maintained at a temperature in the range ofabout 150° C. to less than 300° C. to iridium hexafluoride andtetrasilane. One or more of a flow rate of the tetrasilane, a pulse timeof the tetrasilane, or the temperature of the substrate surface arecontrolled to form an iridium silicide film with essentially no fluorineatoms and a predetermined silicon content.

BRIEF DESCRIPTION OF THE DRAWING

So that the manner in which the above recited features of the disclosurecan be understood in detail, a more particular description of thedisclosure, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of the disclosure and are therefore not to beconsidered limiting of its scope, for the disclosure may admit to otherequally effective embodiments.

The FIGURE illustrates an exemplary process sequence for the formationof a iridium film using a two pulse cyclical deposition techniqueaccording to one embodiment described herein.

DETAILED DESCRIPTION

Embodiments of the disclosure provide methods for depositingiridium-containing films within a broad temperature window, including atvery low temperatures (e.g. room temperature or below). The process ofvarious embodiments use vapor deposition techniques, such as an atomiclayer deposition (ALD) or chemical vapor deposition (CVD) to provideiridium-containing films.

Some embodiments of the disclosure advantageously provide lowtemperature methods to deposit iridium-containing films. Someembodiments of the disclosure advantageously minimize damage to othermaterials by fluorine ions and their byproducts.

A “substrate surface”, as used herein, refers to any portion of asubstrate or portion of a material surface formed on a substrate uponwhich film processing is performed. For example, a substrate surface onwhich processing can be performed include materials such as silicon,silicon oxide, silicon nitride, doped silicon, germanium, galliumarsenide, glass, sapphire, and any other materials such as metals, metalnitrides, metal alloys, and other conductive materials, depending on theapplication. Substrates include, without limitation, semiconductorwafers. Substrates may be exposed to a pretreatment process to polish,etch, reduce, oxidize, hydroxylate, anneal, UV cure, e-beam cure and/orbake the substrate surface. In addition to film processing directly onthe surface of the substrate itself, in the present disclosure, any ofthe film processing steps disclosed may also be performed on anunderlayer formed on the substrate as disclosed in more detail below,and the term “substrate surface” is intended to include such underlayeras the context indicates. Thus for example, where a film/layer orpartial film/layer has been deposited onto a substrate surface, theexposed surface of the newly deposited film/layer becomes the substratesurface. Substrates may have various dimensions, such as 200 mm or 300mm diameter wafers, as well as, rectangular or square panes. In someembodiments, the substrate comprises a rigid discrete material.

“Atomic layer deposition” or “cyclical deposition” as used herein refersto the sequential exposure of two or more reactive compounds to deposita film of material on a substrate surface. As used in this specificationand the appended claims, the terms “reactive compound”, “reactive gas”,“reactive species”, “precursor”, “process gas” and the like are usedinterchangeably to mean a substance with a species capable of reactingwith the substrate surface or material on the substrate surface in asurface reaction (e.g., chemisorption, oxidation, reduction). Thesubstrate, or portion of the substrate, is exposed sequentially to thetwo or more reactive compounds which are introduced into a reaction zoneof a processing chamber. In a time-domain ALD process, exposure to eachreactive compound is separated by a time delay to allow each compound toadhere and/or react on the substrate surface and then be purged from theprocessing chamber. In a spatial ALD process, different portions of thesubstrate surface, or material on the substrate surface, are exposedsimultaneously to the two or more reactive compounds so that any givenpoint on the substrate is substantially not exposed to more than onereactive compound simultaneously. As used in this specification and theappended claims, the term “substantially” used in this respect means, aswill be understood by those skilled in the art, that there is thepossibility that a small portion of the substrate may be exposed tomultiple reactive gases simultaneously due to diffusion, and that thesimultaneous exposure is unintended.

In one aspect of a time-domain ALD process, a first reactive gas (i.e.,a first precursor or compound A) is pulsed into the reaction zonefollowed by a first time delay. Next, a second precursor or compound Bis pulsed into the reaction zone followed by a second delay. During eachtime delay, a purge gas, such as argon, is introduced into theprocessing chamber to purge the reaction zone or otherwise remove anyresidual reactive compound or reaction by-products from the reactionzone. Alternatively, the purge gas may flow continuously throughout thedeposition process so that only the purge gas flows during the timedelay between pulses of reactive compounds. The reactive compounds arealternatively pulsed until a desired film or film thickness is formed onthe substrate surface. In either scenario, the ALD process of pulsingcompound A, purge gas, compound B and purge gas is a cycle. A cycle canstart with either compound A or compound B and continue the respectiveorder of the cycle until achieving a film with the predeterminedthickness.

In an embodiment of a spatial ALD process, a first reactive gas andsecond reactive gas are delivered simultaneously to the reaction zonebut are separated by an inert gas curtain and/or a vacuum curtain. Thesubstrate is moved relative to the gas delivery apparatus so that anygiven point on the substrate is exposed to the first reactive gas andthe second reactive gas sequentially.

One or more embodiments of the disclosure are directed to a method ofdepositing an iridium-containing film. In some embodiments, thedeposition of the iridium-containing film is performed through an ALDprocess. In some embodiments, the deposition of the iridium-containingfilm is performed through a CVD process. In some embodiments, plasmatreatments of a reactant or as a post-treatment after theiridium-containing film is deposited may also be used.

In some embodiments, the first reactive gas comprises an iridiumprecursor. In some embodiments, the iridium precursor comprises iridiumhexafluoride.

In some embodiments, the second reactive gas comprises a reactant. Insome embodiments, the reactant comprises hydrogen gas. In someembodiments, the reactant comprises hydrogen plasma. In someembodiments, the reactant comprises hydrogen radicals.

In some embodiments, the reactant comprises one or more siliconprecursor. Silicon precursors, include but are not limited to, silane(SiH₄), polysilanes (Si_(n)H_(2n+2)), halosilanes (SiX_(a)H_(4−a)), andhalopolysilanes (Si_(n)X_(a)H_(2n+2−a)). In some embodiments, the one ormore silicon precursor contains no halogen atoms. In some embodiments,the silicon precursor consists essentially of tetrasilane. As used inthis manner, the term “consists essentially of” means that the siliconprecursor is greater than or equal to about 95%, 98% or 99% of thestated species, on a molar basis.

In some embodiments, the substrate is exposed to the first reactive gascomprising an iridium precursor and the second reactive gas comprising areactant sequentially. In some embodiments, the substrate is exposed tothe first reactive gas and the second reactive gas simultaneously.

The methods of some embodiments may react precursors in an ALD or CVDprocess to form thin films. Suitable reactants include, but are notlimited to, hydrogen and other co-reactants to make metal films.Suitable reactants also include, but are not limited to, siliconprecursors and other silicon based co-reactants to make M_(x)Si_(y)(metal silicide) films. Plasma treatments of a reactant may also beused.

The FIGURE depicts a method for forming an iridium-containing film on asubstrate in accordance with one or more embodiment of the disclosure.The method 100 generally begins at 102, where a substrate, having asurface upon which an iridium-containing film is to be formed isprovided and placed into a processing chamber. As used herein, a“substrate surface” refers to any substrate surface upon which a filmmay be formed. The substrate surface may have one or more featuresformed therein, one or more layers formed thereon, and combinationsthereof. The substrate (or substrate surface) may be pretreated prior tothe deposition of the iridium-containing film, for example, bypolishing, etching, reduction, oxidation, halogenation, hydroxylation,annealing, baking, or the like.

The substrate may be any substrate capable of having material depositedthereon, such as a silicon substrate, a III-V compound substrate, asilicon germanium (SiGe) substrate, an epi-substrate, asilicon-on-insulator (SOI) substrate, a display substrate such as aliquid crystal display (LCD), a plasma display, an electro luminescence(EL) lamp display, a solar array, solar panel, a light emitting diode(LED) substrate, a semiconductor wafer, or the like. In someembodiments, one or more additional layers may be disposed on thesubstrate such that the iridium-containing film may be at leastpartially formed thereon. For example, in some embodiments, a layercomprising a metal, a nitride, an oxide, or the like, or combinationsthereof may be disposed on the substrate and may have the iridiumcontaining film formed upon such layer or layers.

In some embodiments, the substrate may be exposed to an optional soakprocess 103 prior to beginning the deposition process to form aniridium-containing film on the substrate (as discussed below at 104), asshown in phantom at 103. In one or more embodiments, the method ofdepositing the iridium-containing film on the substrate 104 does notinclude a soaking process.

At 104, an iridium-containing film is formed on the substrate. In someembodiments, the iridium-containing film may be formed via a cyclicaldeposition process, such as atomic layer deposition (ALD), or the like.In some embodiments, the forming of an iridium-containing film via acyclical deposition process may generally comprise exposing thesubstrate to two or more process gases sequentially. In time-domain ALDembodiments, exposure to each of the process gases are separated by atime delay/pause to allow the components of the process gases to adhereand/or react on the substrate surface. Alternatively, or in combination,in some embodiments, a purge may be performed before and/or after theexposure of the substrate to the process gases, wherein an inert gas isused to perform the purge. For example, a first process gas may beprovided to the process chamber followed by a purge with an inert gas.Next, a second process gas may be provided to the process chamberfollowed by a purge with an inert gas. In some embodiments, the inertgas may be continuously provided to the process chamber and the firstprocess gas may be dosed or pulsed into the process chamber followed bya dose or pulse of the second process gas into the process chamber. Insuch embodiments, a delay or pause may occur between the dose of thefirst process gas and the second process gas, allowing the continuousflow of inert gas to purge the process chamber between doses of theprocess gases.

In spatial ALD embodiments, exposure to each of the process gases occurssimultaneously to different parts of the substrate so that one part ofthe substrate is exposed to the first reactive gas while a differentpart of the substrate is exposed to the second reactive gas (if only tworeactive gases are used). The substrate is moved relative to the gasdelivery system so that each point on the substrate is sequentiallyexposed to both the first and second reactive gases. In any embodimentof a time-domain ALD or spatial ALD process, the sequence may berepeated until a predetermined film thickness is formed on the substratesurface.

A “pulse” or “dose” as used herein is intended to refer to a quantity ofa source gas that is intermittently or non-continuously introduced intothe process chamber. The quantity of a particular compound within eachpulse may vary over time, depending on the duration of the pulse. Aparticular process gas may include a single compound or amixture/combination of two or more compounds, for example, the processgases described below.

The durations for each pulse/dose are variable and may be adjusted toaccommodate, for example, the volume capacity of the processing chamber,the capabilities of a vacuum system coupled thereto or the film beingformed. Additionally, the dose time of a process gas may vary accordingto the flow rate of the process gas, the temperature of the process gas,the type of control valve, the type of process chamber employed, as wellas the ability of the components of the process gas to adsorb onto thesubstrate surface. Dose times may also vary based upon the type of filmbeing formed and the geometry of the device being formed. A dose timeshould be long enough to provide a volume of compound sufficient toadsorb/chemisorb onto substantially the entire surface of the substrateand form a layer of a process gas component thereon.

The process of forming the iridium-containing film at 104 may begin byexposing the substrate to a first reactive gas. In some embodiments, thefirst reactive gas comprises an iridium precursor (also referred to asan iridium-containing gas, and the like) and is exposed to the substratefor a first period of time, as shown at 106.

The iridium-containing gas may be provided in one or more pulses orcontinuously. The flow rate of the iridium-containing gas can be anysuitable flow rate including, but not limited to, flow rates is in therange of about 1 to about 5000 sccm, or in the range of about 2 to about4000 sccm, or in the range of about 3 to about 3000 sccm or in the rangeof about 5 to about 2000 sccm. The iridium-containing gas can beprovided at any suitable pressure including, but not limited to, apressure in the range of about 5 mTorr to about 25 Torr, or in the rangeof about 100 mTorr to about 20 Torr, or in the range of about 5 Torr toabout 20 Torr, or in the range of about 50 mTorr to about 2000 mTorr, orin the range of about 100 mTorr to about 1000 mTorr, or in the range ofabout 200 mTorr to about 500 mTorr.

The period of time that the substrate is exposed to theiridium-containing gas may be any suitable amount of time necessary toallow the iridium precursor to form an adequate nucleation layer atopthe substrate surfaces. For example, the iridium-containing gas may beflowed into the process chamber for a period of about 0.1 seconds toabout 90 seconds. In some time-domain ALD processes, theiridium-containing gas is exposed the substrate surface for a time inthe range of about 0.1 sec to about 90 sec, or in the range of about 0.5sec to about 60 sec, or in the range of about 1 sec to about 30 sec, orin the range of about 2 sec to about 25 sec, or in the range of about 3sec to about 20 sec, or in the range of about 4 sec to about 15 sec, orin the range of about 5 sec to about 10 sec.

In some embodiments, an inert gas may additionally be provided to theprocess chamber at the same time as the iridium-containing gas. Theinert gas may be mixed with the iridium-containing gas (e.g., as adiluent gas) or separately and can be pulsed or of a constant flow. Insome embodiments, the inert gas is flowed into the processing chamber ata constant flow in the range of about 1 to about 10000 sccm. The inertgas may be any inert gas, for example, such as argon, helium, neon,combinations thereof, or the like. In one or more embodiments, theiridium-containing gas is mixed with argon prior to flowing into theprocess chamber.

Next, at 108, the process chamber (especially in time-domain ALD) may bepurged using an inert gas. (This may not be needed in spatial ALDprocesses as there is a gas curtain separating the reactive gases.) Theinert gas may be any inert gas, for example, such as argon, helium,neon, or the like. In some embodiments, the inert gas may be the same,or alternatively, may be different from the inert gas provided to theprocess chamber during the exposure of the substrate to the firstprocess gas at 106. In embodiments where the inert gas is the same, thepurge may be performed by diverting the first process gas from theprocess chamber, allowing the inert gas to flow through the processchamber, purging the process chamber of any excess first process gascomponents or reaction byproducts. In some embodiments, the inert gasmay be provided at the same flow rate used in conjunction with the firstprocess gas, described above, or in some embodiments, the flow rate maybe increased or decreased. For example, in some embodiments, the inertgas may be provided to the process chamber at a flow rate of about 0 toabout 10000 sccm to purge the process chamber.

In spatial ALD, purge gas curtains are maintained between the flows ofreactive gases and purging the process chamber may not be necessary. Insome embodiments of a spatial ALD process, the process chamber or regionof the process chamber may be purged with an inert gas.

The flow of inert gas may facilitate removing any excess first processgas components and/or excess reaction byproducts from the processchamber to prevent unwanted gas phase reactions of the first and secondprocess gases. For example, the flow of inert gas may remove excessiridium-containing gas from the process chamber, preventing a reactionbetween the iridium precursor and a subsequent reactive gas.

Next, at 110, the substrate is exposed to a second process gas for asecond period of time. The second process gas reacts with theiridium-containing compound on the substrate surface to create adeposited film. The second process gas can impact the resulting iridiumfilm. For example, when the second process gas is H₂, an iridium film isdeposited, but when the second reactive gas is a silicon precursor, aniridium silicide film may be deposited.

The reactant may be supplied to the substrate surface at a flow rategreater than the iridium precursor. In one or more embodiments, the flowrate of the reactant is greater than about 1 time that of the iridiumprecursor, or about 100 times that of the iridium precursor, or in therange of about 3000 to 5000 times that of the iridium precursor. Thereactant can be supplied for a time in the range of about 1 sec to about30 sec, or in the range of about 5 sec to about 20 sec, or in the rangeof about 10 sec to about 15 sec. The reactant can be supplied at apressure in the range of about 1 Torr to about 30 Torr, or in the rangeof about 5 Torr to about 25 Torr, or in the range of about 10 Torr toabout 20 Torr, or up to about 50 Torr. The substrate temperature can bemaintained at any suitable temperature. In one or more embodiments, thesubstrate is maintained at a temperature less than about 150° C., or ata temperature about the same as that of the substrate during the cobaltprecursor deposition.

In some embodiments, the second reactive gas comprises H₂, or a plasmathereof. In some embodiments, the second reactive gas comprises one ormore silicon precursors or plasmas thereof.

Plasmas used in some embodiments can be a conductively-coupled plasma(CCP) or inductively coupled plasma (ICP) and can be a direct plasma ora remote plasma. In some embodiments, the plasma has a power in therange of about 0 W to about 2000 W. In some embodiments, the minimumplasma power is greater than 0 W, 10 W, 50 W or 100 W.

Next, at 112, the process chamber may be purged using an inert gas. Theinert gas may be any inert gas, for example, such as argon, helium,neon, or the like. In some embodiments, the inert gas may be the same,or alternatively, may be different from the inert gas provided to theprocess chamber during previous process steps. In embodiments where theinert gas is the same, the purge may be performed by diverting thesecond process gas from the process chamber, allowing the inert gas toflow through the process chamber, purging the process chamber of anyexcess second process gas components or reaction byproducts. In someembodiments, the inert gas may be provided at the same flow rate used inconjunction with the second process gas, described above, or in someembodiments, the flow rate may be increased or decreased. For example,in some embodiments, the inert gas may be provided to the processchamber at a flow rate of greater than 0 to about 10,000 sccm to purgethe process chamber.

While the generic embodiment of the processing method shown in theFIGURE includes only two pulses of reactive gases, it will be understoodthat this is merely exemplary and that additional pulses of reactivegases may be used. For example, a nitride film of some embodiments canbe grown by a first pulse containing a precursor gas like iridiumpentachloride, a second pulse with a reducing agent followed by purgingand a third pulse for nitridation. The pulses can be repeated in theirentirety or in part. For example all three pulses could be repeated oronly two can be repeated. This can be varied for each cycle.

Next, at 114, it is determined whether the iridium-containing film hasachieved a predetermined thickness. If the predetermined thickness hasnot been achieved, the method 100 returns to 104 to continue forming theiridium-containing film until the predetermined thickness is reached.Once the predetermined thickness has been reached, the method 100 caneither end or proceed to 116 for optional further processing.

Upon completion of deposition of the iridium-containing film to adesired thickness, the method 100 generally ends and the substrate canproceed for any further processing. For example, in some embodiments, aCVD process may be performed to bulk deposit an iridium-containing filmto a target thickness. For example in some embodiments, theiridium-containing film may be deposited via ALD or CVD reaction of theiridium precursor and hydrogen radicals to form a total film thicknessof about 10 to about 10,000 Å, or in some embodiments, about 10 to about1000 Å, or in some embodiments, about 500 to about 5,000 Å.

While not illustrated within the FIGURE, in some embodiments, theiridium-containing film is deposited by a CVD process. In someembodiments, a thermal CVD process is used. In some embodiments, aplasma enhanced CVD process is used.

During a CVD process, the substrate is positioned on a pedestal which isconfigured to heat the substrate to a suitable processing temperature.

Next, an iridium precursor is flowed into the processing chamber. Theiridium precursor can be a solid or liquid contained in an ampoule. Acarrier gas can be flowed through the ampoule containing the iridiumprecursor to carry vaporized precursor molecules from the ampouleheadspace to the processing chamber. The ampoule can be heated toincrease the vapor pressure of the iridium precursor so that more of theprecursor can be flowed to the processing chamber in a given timeperiod. In some embodiments, the carrier gas comprises one or more ofargon, helium, nitrogen, hydrogen, or other inert gases. The carrier gascomprising the gaseous cobalt precursor is flowed into the processingchamber.

Next, a reactant is flowed into the processing chamber and allowed tomix with the cobalt precursor. The iridium precursor and the reactantcan be mixed prior to flowing into the processing chamber or can remainseparate until both gases enter the processing chamber. Regardless, thesubstrate is exposed to the iridium precursor and the reactantsimultaneously.

The iridium precursor and reactant can be flowed into the processingchamber with the same start and stop times, or one can be pulsed into aflow of the other. For example, in some embodiments, the reactant isflowed into the processing chamber and the carrier gas comprising theiridium precursor is pulsed into the processing chamber or into the flowof reactant. The pulse length and number of pulses can be varied.

Next, the deposition chamber is purged to remove any excess carrier gas,unreacted iridium precursor or reactant, reaction byproducts andreaction products. Purging the deposition chamber stops the formation ofthe iridium-containing film.

At this point it can be determined whether the iridium-containing filmhas achieved a predetermined thickness. If the predetermined thicknesshas not been achieved, the CVD process is repeated to continue formingthe iridium-containing film until the predetermined thickness isreached.

Regardless of the specific method, the temperature of the substrateduring deposition can be controlled, for example, by setting thetemperature of the substrate support or susceptor. In some embodimentsthe substrate is held at a temperature in the range of about −25° C. toabout 500° C., or in the range of about −10° C. to about 350° C., or inthe range of about 0° C. to about 250° C. In some embodiments, thesubstrate is held at a temperature in the range of about −25° C. toabout 250° C., or in the range of about −25° C. to about 300° C., or inthe range of about 150° C. to about 300° C.

In one or more embodiments, the substrate is maintained at a temperatureless than about 500° C., or less than about 400° C., or less than about350° C., or less than about 300° C., or less than about 250° C., or lessthan about 250° C. In one or more embodiments, the substrate ismaintained at a temperature more than about −25° C., or more than about0° C., or more than about 25° C., or more than about 50° C., or morethan about 100° C., or more than about 150° C., or more than about 200°C., or more than about 250° C.

In addition, additional process parameters may be regulated whileexposing the substrate to the iridium-containing process gas and thereactant. For example, in some embodiments, the process chamber may bemaintained at a pressure of about 0.2 to about 100 Torr, or in the rangeof about 0.3 to about 90 Torr, or in the range of about 0.5 to about 80Torr, or in the range of about 1 to about 50 Torr.

In some embodiments, the second reactive gas comprises hydrogen and theresulting film formed is an iridium film. The hydrogen gas may besupplied to the substrate surface at a flow rate greater than theiridium-containing gas concentration. In one or more embodiments, theflow rate of H₂ is greater than about 1 time that of theiridium-containing gas, or about 100 times that of theiridium-containing gas, or in the range of about 3000 to 5000 times thatof the iridium-containing gas. The hydrogen gas can be supplied, intime-domain ALD, for a time in the range of about 1 sec to about 30 sec,or in the range of about 5 sec to about 20 sec, or in the range of about10 sec to about 15 sec. The hydrogen gas can be supplied at a pressurein the range of about 1 Torr to about 30 Torr, or in the range of about5 Torr to about 25 Torr, or in the range of about 10 Torr to about 20Torr, or up to about 50 Torr. The substrate temperature can bemaintained at any suitable temperature. In one or more embodiments, thesubstrate is maintained at a temperature about the same as that of thesubstrate while exposing the substrate to the iridium-containing processgas.

In some embodiments, the second reactive gas comprises hydrogenradicals. The hydrogen radicals can be generated by any suitable meansincluding exposure of hydrogen gas to a “hot-wire”. As used in thisdisclosure, the term “hot-wire” means any element that can be heated toa temperature sufficient to generate radicals in a gas flowing about theelement. This is also referred to as a heating element.

The second reactive gas (e.g., hydrogen), while passing the hot wire, orheating element, becomes radicalized. For example, H₂ passing a hotruthenium wire can result in the generation of H*. These hydrogenradicals may be more reactive than ground state hydrogen atoms.

Suitable co-reactants include, but are not limited to, hydrogen, siliconprecursors and plasmas thereof. In some embodiments, the co-reactantcomprises H₂ or a plasma thereof, argon plasma, nitrogen plasma, heliumplasma, Ar/N₂ plasma, Ar/He plasma, N₂/He plasma and/or Ar/N₂/He plasmato deposit a metal film (e.g., Ir).

In some embodiments, the iridium-containing film comprises greater thanor equal to about 95 atomic percent iridium, or greater than or equal toabout 97 atomic percent iridium, or greater than or equal to about 98atomic percent iridium, or greater than or equal to about 99 atomicpercent iridium, or greater than or equal to about 99.5 atomic percentiridium, or greater than or equal to about 99.8 atomic percent iridium.

In some embodiments, the iridium-containing film contains essentially nofluorine atoms. As used in this manner, the term “contains essentiallyno fluorine atoms” means the iridium-containing film comprises less thanor equal to about 2%, 1% or 0.5% of fluorine atoms on an atomic basis.

In some embodiments, the substrate surface comprises a first materialand a second material. In some embodiments, the first material and thesecond material are the same. In some embodiments, the first materialand the second material are different.

In some embodiments, the first material comprises silicon metal. In someembodiments, the first material consists essentially of silicon. In someembodiments, the second material comprises silicon oxide, siliconnitride or Al₂O₃.

In some embodiments, an iridium-containing film is deposited selectivelyon the first material over the second material. As used in thisspecification and the appended claims, the phrase “depositedselectively”, or similar terms, mean that the subject material isdeposited on the stated surface to a greater extent than on anothersurface. In some embodiments, “selectively” means that the subjectmaterial forms on the selective surface at a rate greater than or equalto about 10×, 15×, 20×, 25×, 30×, 35×, 40×, 45× or 50× the rate offormation on the non-selected surface.

In some embodiments, the silicon content of the iridium-containing filmcan be adjusted through the control of deposition parameters. In someembodiments, one or more of the flow rate of the silicon precursor, thepulse time of the silicon precursor, or the substrate surfacetemperature during deposition is controlled to form aniridium-containing film with a predetermined silicon content.

In some embodiments, the iridium-containing film contains greater than 0percent silicon, or greater than 10 percent silicon, or greater than 20percent silicon, or greater than 25 percent silicon, or greater than 30percent silicon, or greater than 40 percent silicon, or greater than 50percent silicon, on an atomic basis. In some embodiments, theiridium-containing film contains less than 50 percent silicon, or lessthan 40 percent silicon, or less than 30 percent silicon, or less than25 percent silicon, or less than 20 percent silicon, or less than 10percent silicon, or less than 5 percent silicon, on an atomic basis. Insome embodiments, the iridium-containing film contains in the range ofgreater than 0 to about 50 percent silicon on an atomic basis.

Although the disclosure herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent disclosure. It will be apparent to those skilled in the art thatvarious modifications and variations can be made to the method andapparatus of the present disclosure without departing from the spiritand scope of the disclosure. Thus, it is intended that the presentdisclosure include modifications and variations that are within thescope of the appended claims and their equivalents.

What is claimed is:
 1. A method of depositing an iridium-containingfilm, the method comprising exposing a substrate surface maintained at atemperature in the range of about −25° C. to less than room temperatureto repeated deposition cycles, each cycle consisting essentially ofexposing the substrate surface sequentially to iridium hexafluoride anda reactant comprising hydrogen, wherein the substrate surface comprisesa first material and a second material and the iridium-containing filmis deposited selectively on the first material over the second materialand the entire substrate surface is maintained at the temperature in therange of about −25° C. to less than room temperature during the method.2. The method of claim 1, wherein the iridium containing film is greaterthan or equal to about 99.5% iridium atoms.
 3. The method of claim 1,wherein the first material consists essentially of silicon and thesecond material comprises silicon oxide, silicon nitride or Al₂O₃. 4.The method of claim 1, wherein the iridium containing film is depositedat a rate 15 times greater on the first material over the secondmaterial.
 5. The method of claim 1, wherein the iridium containing filmcontains essentially no fluorine atoms.
 6. A method of selectivelydepositing an iridium metal film, the method consisting essentially of:sequentially exposing a substrate surface maintained at a temperature inthe range of about −25° C. to less than room temperature to iridiumhexafluoride and a reactant comprising hydrogen, the substrate surfacecomprising a first material consisting essentially of silicon and asecond material comprising silicon oxide, silicon nitride or Al₂O₃, andthe entire substrate surface is maintained at the temperature in therange of about −25° C. to less than room temperature during the method,provided that the iridium metal film is deposited with a selectivitygreater than or equal to about 15 and contains essentially no fluorineatoms and greater than or equal to about 99.8% iridium atoms.
 7. Themethod of claim 1, wherein the reactant comprises hydrogen plasma. 8.The method of claim 7, wherein the hydrogen plasma comprises one or moreof inductively coupled plasma (ICP) or conductively coupled plasma(CCP).
 9. The method of claim 1, wherein the reactant comprises hydrogenradicals formed by exposing the reactant to a hot wire.
 10. The methodof claim 1, wherein the entire substrate surface is maintained at atemperature in the range of about −25° C. to about 0° C. during themethod.